Join Deke McClelland for an in-depth discussion in this video Previewing clipping, part of Photoshop CS4 One-on-One: Advanced.
- View Offline
In this exercise I'm going to show you a special top secret trick for previewing the exact pixels inside of your image that are getting clipped to either to black or white. When you are working inside either the Levels dialog box or here inside of the Adjustments palette, when you are working with an adjustment layer. Now I have gone ahead and saved my progress so far, and I have brightened the image up quite nicely actually I think, I'm starting to bring out some of the noise in this high noise image in the first place, but that's okay. It's kind of artsy, I think it's nice. Now here I have got the Composite Histogram layer turned on and selected, the Auto color clip blah. Blah, blah layer is not selected and it's also turned off.
And you can compare the two if you wanted to. Here is the Composite modification that I have applied so far. Meaning that it affects all of the channels at once, that's what I mean by composite, and I'll tell you what that means in a couple of exercise. I'll show you how to adjust an image on a channel by channel basis shortly. But anyway, in the meantime I'm going to go ahead and turn off Composite Histogram and then turn on Auto color. And the Auto color modification that we applied a couple of exercises ago now is actually a more subtle adjustment, and I kind of like it better this far. We'll ultimately be working from it when we apply our channel by channel modifications, which will end up getting us the effect that we are really looking for. But I just want you to see that the Auto functions are actually quite intelligent in many cases. Anyway, let's go and turn off and go back to my less intelligent and less subtle composite modification that I've applied so far.
And I wanted to go ahead and show you that wonderful trick that I was telling you about. Here's what you do. So if you just drag the black slider, notice you are just seeing the colors change, and you are just hoping that you are not clipping anything, and you are just trying to pay attention to the histogram here. But if you want to see the clipping, you can either go up here in the Adjustment palette to the menu icon right there, and you can choose this command, Show Clipping for Black/White Points, but then you are always going to see the clippings no matter what. But I'll go and turn it on, so you can see what I'm talking about. And now if you drag this guy, notice you are seeing the sort of clip preview.
I'll tell you what the clip preview means in just a moment, for both the black slider triangle and for the white slider triangle, and you have no way to turn it off. You have no way to view the image naturally and normally, except to go back to the command and turn this darn thing off. Whereas, the technique I'm about to show you is much better in my opinion, because you can turn it on and off on the fly just with the help of the Alt or Option key. So anyway, let's go and turn this command off, and now notice, if I don't press any key, I just see the image change normally like so.
But let's start with white, because it makes little more sense. If I press and hold the Alt key or the Option key on the Mac, and go ahead and keep that key down and drag that white slider triangle, and I say keep the key down, because notice, as soon as I release the key and start dragging the white point around a little more there, then I just see the standard preview of the image. I have to press and hold the Alt key in order to see this clipping preview. Now what we are seeing here is anything that is black, when you are moving the white slider triangle with the Alt key down or the Option key on the Mac, anything that's black is protected, meaning it's not getting clipped.
Anything that goes to white is getting clipped in all three channels. So that's definitely dangerous. When you see white that is the danger sign. If you are seeing some sort of color go on there, like red and yellow in our case, then that means it's just getting clipped in one or a couple of channels. Now see what we are seeing right here. I'll just leave the white point alone for a moment. I'm actually holding my mouse button down, and holding the Alt or Option key down at the same time. So I have got bunch of things held down, for you I'm doing this. It's quite painful for me to do this. So notice where we are seeing red, I just want you to get a sense what's going on. When we are seeing red, it means it's clipping just in the red channel, not in the green or blue channels. When we are seeing green, and that's over on the left side of the screen near the T in the toolbox, where we are seeing that little patch of green, that means it's getting clipped in the green channel, but not in the red or blue.
If we were seeing blue, that would just be getting clipped in the blue channel, but we were not seeing blue. If we are seeing some other color, like a secondary color like yellow, in the case of yellow it's getting clipped in both the red and the green channel, and it's only not getting clipped in the blue channel, which means we don't have much not clipping going on. So yellow is pretty dangerous, magenta would be clipping in both red and blue, and then cyan would be clipping in both green and blue. So if you are just seeing one color like red, green, or blue, then that might be okay. If you are seeing a dual color, secondary color like yellow or magenta or cyan, then that's starting to get dangerous, and if you are seeing white, my goodness, you've got major clipping going on. That's all three channels together.
Also if you are seeing big patches as we are at this point, then that's probably not the good thing either. You don't want to clip red, and especially in a portrait shot, because that's where the majority of the information is, is in the red channel. So what you want is just mostly black, and if you are going to have little patches of color show up, you want them to be sporadic, and you want them to be pretty spread apart from each other. So just little tiny patches, maybe individual pixels here and there is the best case. All right, so 191, 190, something on those lines is going to work out just fine, and I'm looking at this value over here inside the Adjustment palette now. So I'm shifting my focus. All right, let's do the same thing by Alt dragging or Option dragging the black slider.
Now, wherever we are seeing white, in the case of the black point, wherever we are seeing white is protected, and wherever we are seeing black is terrible. I mean, it's clipping in all three channels. So black is very dangerous in this case. So the whole thing gets turned its head. It really gets turned on its head though, in the fact that otherwise we are seeing complimentary colors. So yellow, means it's only getting clipped in the blue channel. Now I know you are sitting and thinking, why, why is that way? Why they have to make it that way? Because, think of it this way. It's turning black in the blue channel, it's not turning black in either the red or the green channel, so black and blue plus white and red and green gives you yellow. So, it's just the way it works. So you have to look for the compliment.
It gets pretty complicated, because yellow means blue, and magenta means green, right? And cyan means red, and so everybody's compliment is, it worked there, and red would mean that it is getting clipped in both the green and the blue channels, because it's an absence of cyan. So it gets a little topsy-turvy. So what I'm going to tell you is you want this, you just want a few speckles for your shadows. Mostly you want to see white, just a few speckles in other colors, and you want to try to avoid black if you can, and that's going to give you a good effect. All right, then I'll go ahead and release, and I know that I'm not clipping much this way, and it's just because I want to subtle adjustment. I'm going to take gamma down, down to 0.95, so we have a darker image that work here. And tell you what, I'm only going to show you one more thing, that's a composite thing, before we move on to the channel by channel of adjustments and that's going to be output levels here. Very short exercise coming up on output levels, because they're not all that useful, and then we are really going to dig in, and we are going to see how to correct this image or any image for that matter, on a channel by channel basis which is where the Levels Command really shines.
Recommended prerequisite: Photoshop CS4 One-on-One: Fundamentals.
Download Deke's customized keyboard layouts and color settings for Photoshop under the download feature.
- Using blend modes, adjustment layers, and layer styles
- Organizing a layered composition so it is fluid and editable
- Creating and editing type in Photoshop
- Using blur effectively
- Using adjustment layers to add color
- Combining layers into a clipping mask
- Working with Camera Raw